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Options for auto leveling?

Posted by TheBoilingDumpling 
Re: Options for auto leveling?
March 06, 2015 05:57PM
Quote
dc42
Yes. A single beam is OK as a proximity sensor, but poor as a height monitoring device (which is what we need) because its sensitivity depends on how reflective the surface is. The RepRapPro Ormerod uses such a sensor, and you have to put white targets at the corners of the bed (which are the probing points). My differential IR sensor uses 2 beams to avoid that. So it works on a surface of plain glass, Kapton tape, glue etc. However, if the bed is transparent and the surface underneath is very reflective, the trigger height is affected a little by the reflection from behind the bed.

What if I used a single beam, but the bed was all white? I mean reflective for the beam? Wouldn't that be the same as using white targets at the corners of the bed, but you would be able to actually level around the whole bed in case it was not completely flat?
Re: Options for auto leveling?
March 06, 2015 06:06PM
Quote
TheBoilingDumpling
What if I used a single beam, but the bed was all white? I mean reflective for the beam? Wouldn't that be the same as using white targets at the corners of the bed, but you would be able to actually level around the whole bed in case it was not completely flat?

Yes, if the bed is a very uniform shade of white - or some other colour, as long as it reflects whatever wavelength of visible or IR light you use reasonably well.



Large delta printer [miscsolutions.wordpress.com], Robotdigg SCARA printer, Crane Quad and Ormerod

Disclosure: I design Duet electronics and work on RepRapFirmware, [duet3d.com].
Re: Options for auto leveling?
March 06, 2015 06:35PM
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TheBoilingDumpling
Quote
nophead
Capacitive sensors detect insulators at a different distance to conductors. If you have an insulator over a conductor it will trigger at a bigger distance than either on their own. So if you have glass over metal it responds partly to the proximity of the metal and partly to the thickness and proximity of the glass, not to the top surface of the glass as you would want.

Capacitive, inductive, hall effect, and optical are all analogue measurements compared with a threshold. They can be affected by supply voltage, temperature and stray fields.

My preferred solution is a pair of gold contacts, you don't get much more digital than that. Pulled together by a magnet, pushed apart by a rod and pushed further to latch in an up position held by the magnet. The only electronics requires is a digital input pin.
You're talking about this right? [www.openbeamusa.com] I have seen a bunch of variation of auto leveling on Delta bots.

No, my own design described here: [forums.reprap.org]

What are you putting on top of your aluminium to print on?


[www.hydraraptor.blogspot.com]
Re: Options for auto leveling?
March 06, 2015 06:55PM
Looks like I'll have to decide on which bed and leveling system I want,

Edited 1 time(s). Last edit at 03/06/2015 07:29PM by TheBoilingDumpling.
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